Brazilian Journal of Chemical Engineering ( IF 1.5 ) Pub Date : 2021-09-09 , DOI: 10.1007/s43153-021-00152-z André Silveira Felipe 1 , Felipe Orlando da Costa 1 , Felipe Leonardo Bacelos 1 , Irineu Petri Júnior 1
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Microwave ovens function through the emission of electromagnetic waves, which reflect off the walls of the cavities causing local fluctuations to the electromagnetic field. In multimode cavities, multiple hotspots are generated due to the presence of various nodes, causing the localized overheat. Understanding the location of the hotspots is important to improve the heating efficiency and homogeneity of the microwave. This work aimed to propose an innovative technique for mapping the hotspots inside the multimode cavities microwave, using a resistive sheet made of polypropylene and activated carbon in contents of 5, 10 and 20%. To validate the experimental mapping technique, numerical simulations were used to predict the electromagnetic fields inside the cavity, and the simulations were then compared to the experimental result. The numeric models were validated through the experimentally determined output power. The experimental mapping results showed it was possible to reproduce clear and easy identifiable hotspots in different heights inside cavities using resistive sheets with activated carbon contents of 10 and 20%. The numerical simulations showed results for the output power that were statistically equal to the experimental results, validating its application for the prediction of the electromagnetic and thermo fields. Comparing the experimental and numerical mapping of the hotspots, a consistent match was verified between the generated profiles. Thus, the developed mapping technique managed to predict adequately the hotspots inside microwave cavities, which is useful for applications such as scale-ups and the optimization of industrial cavities.
Graphic abstract
中文翻译：
电阻片微波腔内热点映射技术的研制
微波炉的工作原理是发射电磁波，电磁波从腔壁反射，导致电磁场局部波动。在多模腔中，由于存在各种节点，会产生多个热点，导致局部过热。了解热点的位置对于提高微波的加热效率和均匀性很重要。这项工作旨在提出一种创新技术，用于绘制多模腔微波内部的热点，使用由聚丙烯和活性炭制成的电阻片，其含量为 5%、10% 和 20%。为了验证实验映射技术，使用数值模拟来预测腔内的电磁场，然后将模拟结果与实验结果进行比较。通过实验确定的输出功率验证了数值模型。实验测绘结果表明，使用活性炭含量为 10% 和 20% 的电阻片，可以在空腔内的不同高度重现清晰易识别的热点。数值模拟显示输出功率的结果在统计上与实验结果相同，验证了其在电磁场和热场预测中的应用。比较热点的实验和数值映射，验证了生成的配置文件之间的一致匹配。因此，开发的绘图技术成功地充分预测了微波腔内的热点，这对于工业腔的放大和优化等应用非常有用。
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